More frequent showers and thunderstorm days under a warming climate: evidence observed over Northern Eurasia from 1966 to 2000

This study uses 3-hourly synoptic observations at 547 stations to examine changes in convective and non-convective precipitation days and their associations with surface air temperature and specific humidity over Northern Eurasia. We found that convective days (showers and those associated with thunder and lightning) have become more frequent possibly at the expense of non-convective ones for all seasons during the study period of 1966–2000. The mean trends for convective day fraction (total convective precipitation events divided by all precipitation events for each season) are very similar among all four seasons at around 0.61–0.76% per year averaged over the study region. The temperature and humidity associated with convective events are on average 2.4–5.6 °C and 0.4–0.9 g/kg higher than those of non-convective events, respectively. This study suggests that surface warming and moistening lead to increased tropospheric static instability, contributing to the observed trends.